Dose-Response Relationships Between Gonadal Steroids and Bone, Body Composition, and Sexual Function in Aging Men.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 32480409 · doi:10.1210/clinem/dgaa318
What was done
In a 16-week randomized controlled trial, 177 men aged 60 to 80 years received goserelin acetate to suppress endogenous gonadal steroids combined with daily 1% testosterone gel at doses of 0 g (placebo), 1.25 g, 2.5 g, 5 g, or 10 g, or placebos for both medications (controls). The trial evaluated dose-response relationships by measuring changes in bone resorption via serum C-telopeptide (CTX), body fat via dual energy X-ray absorptiometry, and self-reported sexual desire and erectile function.
What was found
Serum CTX increases exceeded controls in men with testosterone concentrations of 0 to 99, 100 to 199, 200 to 299, and 300 to 499 ng/dL. Increases in total body fat, subcutaneous fat, and thigh fat exceeded controls only at testosterone concentrations of 0 to 99 or 100 to 199 ng/dL. Sexual desire and erectile function remained indistinguishable from controls until testosterone levels dropped below 100 ng/dL. Exact numerical effect sizes and confidence intervals were not reported in the abstract.
Why it matters
Physiological changes in bone resorption, adiposity, and sexual function occur at distinct testosterone thresholds in aging men. These findings demonstrate that standard statistical definitions of normal testosterone fail to reflect tissue-specific physiological responses.
Limits
The study was short in duration (16 weeks) and had a modest sample size across six study arms. It utilized acute pharmacologic suppression rather than assessing natural age-related hormone decline, and clinical outcomes such as fractures or cardiovascular events were not measured.
Cited by
- context Specific symptoms of testosterone deficiency emerge at distinct population thresholds: bone loss around 300 ng/dL, decreased frequency of sexual thoughts at 215 ng/dL, and loss of vigor around 290 ng/dL.